Embedded Percolated Metallic Networks With Ultrathin Conformal Coverage for Enhanced Silicon Hot‐Electron SWIR Photodetection and Single‐Pixel Imaging

ABSTRACT Hot‐electron photodetection based on internal photoemission provides an attractive alternative to extend silicon photodetectors into the short‐wave infrared (SWIR) regime. However, most reported plasmonic nanostructures rely on complex, costly, and fabrication‐sensitive nanofabrication processes and exhibit inefficient hot‐electron transport and extraction, which together hinder practical applications. Here, we report embedded percolated fractal metallic networks with ultrathin conformal coverage that enable efficient hot‐electron transport and extraction, realized through a scalable, lithography‐free, and fabrication‐tolerant process based on thin‐film deposition and metal‐assisted chemical etching. The embedded percolated fractal metallic architecture gives rise to densely distributed plasmonic hotspots and strong local electromagnetic field enhancement, enabling broadband hot‐electron generation, while simultaneously suppressing hot‐electron thermalization losses, alleviating momentum mismatch, and maximizing the emission momentum space through the formation of a quasi‐omnidirectional Schottky interface. Consequently, the device achieves a responsivity of 2.78 mA/W at a wavelength of 1.3 µm, outperforming plasmonic nanoneedle arrays. Furthermore, we demonstrate SWIR single‐pixel imaging with a spatial resolution of 64 × 64 pixels, including perspective imaging through silicon wafers, as well as optical communication for information transmission. This work establishes a simple, lithography‐free, and fabrication‐tolerant strategy for scalable, complementary metal‐oxide semiconductor (CMOS)‐compatible silicon sub‐bandgap hot‐electron photodetectors for imaging and optical communication applications.